Investigators are searching for more than 100 women they say were victimized by a registered sex offender who secretly shot videos up their skirts.

Mylyn Johnson of the Antelope Valley was arrested in March and faces 15 felony charges including false imprisonment, burglary and several counts of "unlawful recording of undergarments," according to a statement from the Los Angeles County Sheriff's Department.

Detectives found thousands of videos of more than 100 women on Johnson's phone, storage devices and inside his home. Authorities said the women ranged in age from their teens to about 50 years old.

Johnson secretly recorded the women throughout the Antelope Valley, including a Salvation Army store, the Lancaster International Shopping Mall, a Metrolink train station and Union Station, the Sheriff’s Department said. Officials believe some of the recordings date as far back as August 2012.

Only 10 victims have been identified.

Authorities say that on one occasion, Johnson identified himself as a security officer at a K-Mart store and detained a woman for shoplifting. He then ordered the woman to expose herself as part of the search, the sheriff’s statement said.

Johnson would also commonly engage the victims in conversation before identifying himself as a tattoo artist, a rap musician or as being with "Loyal Luck Television," the statement said.

He was arrested in March by security at a Target store in Lancaster.

Authorities are asking anyone with information to call the Special Victims Bureau at (877) 710-5273 or via email at SpecialVictims@lasd.org. Anonymous tipsters may call (800) 222-TIPS (8477).